Formation Energy Profiles of Oxygen Vacancies at Grain Boundaries in Perovskite-Type Electroceramics

Oxygen vacancy formation energies play a major role in the electric field-assisted abnormal grain growth of technologically relevant polycrystalline perovskite phases. The underlying effect on the atomic scale is assumed to be a redistribution of cationic and anionic point defects between grain boundaries (GBs) and the bulk interior regions of the grains due to different defect formation energies in the structurally different regions, accompanied by the formation of space charge zones. Using atomistic calculations based on classical interatomic potentials, optimized structures of the symmetric tilt GBs sigma 5(210)[001] and sigma 5(310)[001], and of the asymmetric tilt GB (430)[001]||(100)[001] in the electroceramic perovskite materials SrTiO3, BaTiO3, and BaZrO3, are derived and discussed. Profiles of oxygen vacancy formation energies across those GBs are presented and their dependence on composition and GB type is discussed.

Automated summary

Oxygen vacancy formation energies play a crucial role in the abnormal grain growth of polycrystalline perovskite phases under electric field assistance. This is due to the redistribution of cationic and anionic defects between grain boundaries and bulk regions, accompanied by the formation of space charge zones. Atomistic calculations based on classical interatomic potentials are used to derive and discuss optimized structures of various grain boundaries in SrTiO3, BaTiO3, and BaZrO3 materials. The profiles of oxygen vacancy formation energies across these grain boundaries are presented, and their dependence on composition and grain boundary type is discussed.